Fiber-Optic Transceivers

Over the years, discrete solutions in most of the datacom applications are replaced by fiber optic transceivers (TRX). Each TRX is a combination of a transmitter (Tx) and a receiver (Rx) in a single common housing. The transmitter unit, with either a light-emitting diode (LED) or an edge or vertical-emitting laser diode (LD) as its radiation source, and the receiver unit, which in most cases is a positive-intrinsic-negative (PIN) photodiode, are connected together to the transmission medium, either multimode or single-mode fiber. Thus, transceivers characteristically have duplex optical receptacles at one side of the housing, which fit to the corresponding duplex connectors contrary to typical telecom applications with single-fiber optic connectors. The implementation of more or less electronics with integrated circuits and passive components into the Tx and Rx units depends on the application. This chapter discusses the aspects of operation and the application of fiber optic transceivers in the physical layer (PHY), along with some innovative tendencies for the integration of more data transport functions into these components or for a significant reduction of size and power consumption.